Lamina propria and circulating interleukin-6 in newly diagnosed pediatric inflammatory bowel disease patients

Understanding cytokine production patterns in early mucosal lesions of pediatric patients newly diagnosed with inflammatory bowel disease (IBD) may be critical to understanding IBD pathogenesis. Interleukin-6 (IL-6) has a central role in a multitude of immune system reactions; however, inconsistent lamina propria and serum IL-6 has been reported in IBD patients. Newly diagnosed pediatric IBD patients have not previously been evaluated for lamina propria or serum IL-6. Serum and intestinal lamina propria biopsy whole organ culture supernatants were evaluated by ELISA for IL-6 obtained from newly diagnosed IBD patients, before initiation of immunomodulatory therapies. Levels of lamina propria IL-6 demonstrated significant correlation with graded severity of histological inflammation (p < 0.001). Log-transformed serum and organ culture IL-6 levels demonstrated significant correlation (p < 0.0001, R2= 0.6226). Assigning a demarcation level of >400 pg/ml, serum IL-6 concentrations were a superior marker for the presence of microscopic intestinal inflammation than erythrocyte sedimentation rate (ESR), with a sensitivity of 82%, specificity of 100%, positive predictive value of 100%, and negative predictive value of 82%. When evaluating subtypes of IBD, serum IL-6 levels were correlated more significantly with active disease in ulcerative colitis patients (p = 0.01, R2= 0.74) than in Crohn's disease patients (p = 0.21, R2= 0.33). This study outlines graded production of IL-6 in intestinal lamina propria and serum of newly diagnosed pediatric IBD patients, confirming the presence of IL-6 in early IBD patients. In addition, serum IL-6 may be a good predictor of IBD in pediatric patients with suspected or newly diagnosed IBD.